JP2007086399A - Optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having a photo-alignment layer that can develop alignment regulating force by irradiation with light and an optical functional layer containing a liquid crystalline compound, wherein the adhesiveness between the photo-alignment layer and the optical functional layer can be increased and durability of each layer can be improved. <P>SOLUTION: The optical element comprises at least a support, a photo-alignment layer that can develop alignment regulating force by irradiation with light, and an optical functional layer containing a liquid crystalline compound. The photo-alignment layer is formed from a photo-alignment layer forming composition containing a compound having at least one kind of group selected from an epoxy group, oxetanyl group and vinyloxy group. The optical functional layer is formed from an optical functional layer forming composition containing a compound having at least one kind of group selected from an epoxy group, oxetanyl group and vinyloxy group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element such as a retardation plate, a polarizing plate, a display color filter, and the like, and in particular, an alignment film capable of expressing an alignment regulating force by light irradiation, and an optical functional layer comprising a liquid crystalline compound It is related with the optical element provided with.

  In general, liquid crystals are used as a medium for display elements such as TN (twisted nematic) type and STN (super twisted nematic) type by utilizing the reversible mobility of molecular arrangement, as well as their orientation and refraction. Utilizing the rate anisotropy, it is also used as an optical element such as a retardation plate, a polarizing plate, and a color filter for display.

  Here, regarding the latter application, in recent years, many optical elements including a liquid crystal layer made of a polymerizable liquid crystal material as a refractive index anisotropic layer have been proposed. Specifically, Patent Document 1 discloses an optical element having functions of wavelength selective reflectivity and polarization selective reflectivity, which is manufactured using a special polymerizable liquid crystal compound. Patent Document 2 discloses a birefringent plate manufactured using a polymerizable liquid crystal compound having a rod-like structure. Further, Patent Document 3 discloses an optical compensation sheet produced using a polymerizable liquid crystal compound having a disk-like structure.

  By the way, as such an optical element, a plastic film or the like is used as a support, and an optical functional layer having an alignment property and refractive index anisotropy made of a polymerizable liquid crystal material is laminated on the support through an alignment film. What is used is generally used.

  Here, the alignment film provided between the support and the optical functional layer has an alignment regulating force that regulates the alignment direction of the liquid crystal molecules in the optical functional layer having refractive index anisotropy. Such an alignment film is formed, for example, by forming a polymer layer such as oriented polyimide or polyvinyl alcohol on a support and then subjecting the polymer layer to an alignment treatment such as a rubbing treatment. be able to. In addition, when rubbing is performed as an alignment process, there is a problem that static electricity and dust are generated on the surface of the alignment film. Therefore, a technique for expressing the alignment regulating force in the alignment film without performing the rubbing process has been studied. ing. One of them is a photo-alignment method in which alignment regulation force (anisotropy) is generated on the surface of the alignment film by irradiating light. An alignment film used for the photo-alignment method is called a photo-alignment film. The photo-alignment method has an advantage that the director direction of the liquid crystal in the optical functional layer can be easily controlled as compared with the rubbing treatment.

  Such photo-alignment methods include “photoisomerization” in which only the molecular shape is deformed to reversibly change the alignment state, and “photoreaction type” in which the molecule itself is changed. The latter “photoreactive type” is further divided into a dimerization type, a decomposition type, a binding type, a decomposition-bonding type, and the like.

  In an optical element composed of a support, a photo-alignment film and an optical functional layer as described above, it is of course important that the optical characteristics of each layer of the optical element are good. It is also important that the durability is good. Regarding the latter problem, for example, when the adhesion between the optical alignment film constituting the optical element and the optical functional layer is poor, there is a problem that the optical functional layer is easily peeled off from the optical alignment film.

In order to solve such problems, conventionally, the following methods have been proposed. Patent Document 4 proposes a method for eliminating stress cracks and improving the adhesion of the optical functional layer by disposing a layer exhibiting an indentation elastic modulus of less than 2 Gpa between the support and the photo-alignment film. This method does not directly attach the photo-alignment film and the optical functional layer, and is insufficient in practical use.
JP 2002-533742 A Japanese Patent Application Laid-Open No. 5-215921 JP-A-8-338913 JP 2004-139084 A

  Therefore, the present invention solves the above-mentioned problems of the prior art and is an optical element including a photo-alignment film capable of developing an alignment regulating force by light irradiation and an optical functional layer containing a liquid crystalline compound. Then, it aims at providing the optical element which can improve the adhesiveness between a photo-alignment film and an optical function layer, and can improve the durability of each layer.

  In order to solve the above-described problems, an optical element of the present invention includes an optical functional layer including at least a support, a photo-alignment film capable of expressing an alignment regulating force by light irradiation, and a liquid crystalline compound. The device, wherein the photo-alignment film is formed from a composition for forming a photo-alignment film including a compound having one or more groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group, The optical functional layer is formed from a composition for forming an optical functional layer containing a compound having one or more groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group. To do.

  According to the present invention, both the composition for forming a photo-alignment film and the composition for forming an optical functional layer capable of expressing an alignment regulating force by light irradiation are both compounds having an epoxy group, an oxetanyl group, or a vinyloxy group. Therefore, the affinity between the photo-alignment film and the optical function layer is high, and the adhesion at the interface between the photo-alignment film and the optical function layer can be improved.

  Moreover, since the epoxy group, oxetanyl group, or vinyloxy group contained in the composition for alignment films can be cationically polymerized, the strength of the photo-alignment film can be improved. Accordingly, the optical element of the present invention can effectively solve the problem that the optical functional layer is peeled off.

  FIG. 1 shows an example of a basic layer structure of the optical element of the present invention. In FIG. 1, 1 is a support, 2 is a photo-alignment film formed on the support 1, and 3 is an optical functional layer formed on the photo-alignment film 2. FIG. 2 shows still another example of the basic layer structure of the optical element of the present invention. The optical element of FIG. 2 is obtained by providing a barrier layer 4 between the support 1 and the photo-alignment film 2 in the optical element of FIG. Examples of the optical element having these layer structures include a retardation plate, a polarizing element, and a color filter for display.

  In the present invention, “(meth) acryloyl group” means either “acryloyl group” or “methacryloyl group”.

<Support>
The type of the support is determined according to the intended use of the optical element, but generally a transparent polymer film, a transparent glass plate or the like is used. Transparent means that the transmittance is 80% or more. An optically isotropic polymer film is generally used as the transparent polymer film, and examples thereof include a cellulose film such as triacetyl cellulose, a film made of a cycloolefin polymer, and a norbornene polymer.

  Depending on the type of liquid crystal display mode, an optically anisotropic polymer film may be used as the transparent support. As the optically anisotropic polymer film, polycarbonate, polysulfone, polyethersulfone, polyetheretherketone, poly (meth) acrylate, cycloolefin-based polymer, norbornene-based polymer, cellulose ester, or the like is used. An optically anisotropic polymer film is generally obtained by stretching. An optically anisotropic cellulose ester film can be obtained by using a retardation increasing agent, lowering the oxidation degree of cellulose acetate, and producing the film by a cooling dissolution method.

The thickness of the support is preferably 20 μm to 500 μm.
In order to improve the adhesion between the support and the alignment film, the support may be subjected to surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet treatment, flame treatment) to form a barrier layer described later. May be.

<Optical function layer>
The composition for forming an optical functional layer used for the optical functional layer in the optical element of the present invention has a liquid crystallinity and includes one compound having an epoxy group, an oxetanyl group, or a vinyloxy group. It may be a compound or a mixture of a plurality of compounds, and is not particularly limited.

  The composition for forming an optical functional layer used in the present invention may contain the following component (A), or may contain the following components (B) and (C) at the same time. Or you may contain the following (B) component and (D) component simultaneously, and may contain the following (E) component and (D) component simultaneously.

  That is, the first preferred optical functional layer forming composition includes a component (A) containing a liquid crystalline compound having one or more groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group. It is done. Such a liquid crystalline compound may contain a (meth) acryloyl group. In the present specification, the liquid crystal compound means either a polymer liquid crystal or a polymerizable low molecular liquid crystal.

  The second preferred composition for forming an optical functional layer contains a liquid crystalline compound having a (meth) acryloyl group as the component (B), and (meth) acryloyl in the molecule as the component (C). Examples thereof include those having a group and a compound having at least one group selected from an epoxy group, an oxetanyl group, and a vinyloxy group. The component (C) may be a non-liquid crystalline compound or a liquid crystalline compound.

  As the third preferred optical functional layer forming composition, as the component (B), a liquid crystalline compound having a (meth) acryloyl group, and as the component (D), an epoxy group, an oxetanyl group in the molecule, And those containing polyfunctional compounds containing two or more functional groups selected from vinyloxy groups.

  The fourth preferred optical functional layer forming composition has (meth) acryloyl group as component (E) and at least one selected from an epoxy group, an oxetanyl group, and a vinyloxy group. Examples of the liquid crystalline compound having a group and the component (D) include those containing a polyfunctional compound containing two or more functional groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group in the molecule.

  The mass ratio of the liquid crystalline compound to the non-liquid crystalline compound in the composition for forming an optical functional layer is preferably 60/40 or more and 100/0 or less. When the mass ratio of the liquid crystal compound to the non-liquid crystal compound is less than 60/40, the alignment of the liquid crystal compound is disturbed and the haze is increased.

  The total amount of epoxy groups, oxetanyl groups, and vinyloxy groups contained in the composition for forming an optical functional layer is preferably 0.3 mmol or more per 1 g of components other than the solvent in the composition for forming an optical functional layer. When the total amount of the epoxy group, the oxetanyl group, and the vinyloxy group was less than 0.3 mmol per 1 g of the component other than the solvent in the composition for forming an optical functional layer, the epoxy group, the oxetanyl group, and the vinyloxy group were selected. Adhesiveness with a photo-alignment film having one or more groups is low.

  The following five types are mentioned as a more specific preferable form of the composition for optical function layer formation used for this invention.

  Form 1: An optical functional layer forming composition comprising a polymer liquid crystal having an epoxy group, an oxetanyl group or a vinyloxy group. Alternatively, when the polymer liquid crystal does not have an epoxy group, an oxetanyl group, or a vinyloxy group, the composition for forming an optical functional layer is a non-liquid crystal having an epoxy group, an oxetanyl group, or a vinyloxy group in addition to the liquid crystalline compound. Containing sexual compounds.

  Form 2: An optical functional layer forming composition containing a polymerizable low-molecular liquid crystal having an epoxy group, an oxetanyl group or a vinyloxy group. Since alignment is easier than the polymer liquid crystal of Form 1, it is preferable. Since the epoxy group or oxetanyl group has a smaller shrinkage in curing than the (meth) acryloyl group, the adhesiveness is superior to the case where only the polymerizable low-molecular liquid crystal having only the (meth) acryloyl group is used. .

  Form 3: A polymerizable low-molecular liquid crystal having a (meth) acryloyl group and a non-liquid crystalline compound having a polyfunctional (two or more functional groups, the same shall apply hereinafter) epoxy group, a polyfunctional oxetanyl group or a polyfunctional vinyloxy group It is a mixed composition for forming an optical functional layer. Since alignment is easier than the polymer liquid crystal of Form 1, it is preferable. The epoxy group or oxetanyl group has a smaller shrinkage in curing than the (meth) acryloyl group, and therefore has better adhesion than the case of using only a polymerizable low-molecular liquid crystal that uses only the (meth) acryloyl group. Become. However, since Form 3 also contains a (meth) acryloyl group, there is an advantage that photocuring is generally faster than Form 2 that does not contain a (meth) acryloyl group.

  Form 4: Composition for forming an optical functional layer comprising a polymerizable low-molecular liquid crystal having a (meth) acryloyl group, one or more (meth) acryloyl groups, and a compound having at least one epoxy group, oxetanyl group or vinyloxy group It is a thing. Since alignment is easier than the polymer liquid crystal of Form 1, it is preferable. Since the compound having an epoxy group, oxetanyl group or vinyloxy group further has a (meth) acryloyl group, it is harder to cure with a smaller amount of UV irradiation and has a better durability of the optical functional layer than the third embodiment. There are advantages.

  Form 5: Optical functional layer containing a polymerizable low-molecular liquid crystal having a (meth) acryloyl group and having an epoxy group, oxetanyl group or vinyloxy group, and a polyfunctional compound having an epoxy group, oxetanyl group or vinyloxy group It is a composition for formation. Since alignment is easier than the polymer liquid crystal of Form 1, it is preferable. Since the epoxy group or oxetanyl group has smaller curing shrinkage than the (meth) acryloyl group, the adhesiveness is superior to that of the (meth) acryloyl group alone.

  As the compound of the component (C), for example, a compound represented by the following general formula (1), (2), (3), (4) or (5) can be used.

(R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an optionally branched alkyl group having 1 to 12 carbon atoms, R ₃ is hydrogen or a methyl group, and m is an integer of 1 to 6. N is 0 or an integer of 1 to 6, p and q are 0 or an integer, and the sum of p and q is 2 to 8.)

  If necessary, a non-liquid crystalline compound having one or more groups selected from an epoxy group, an oxetanyl group and a vinyloxy group can be added to the composition for forming an optical functional layer used in the present invention. In addition to the above components, additives such as a solvent, a radical and / or a cationic polymerization initiator (mainly a photopolymerization initiator), a surfactant, a leveling agent, and a polymerization inhibitor can be used.

Liquid crystalline compounds:
The liquid crystalline compound contained in the composition for forming an optical functional layer used in the present invention only needs to have nematic regularity, smectic regularity, or cholesteric regularity. Either can be used. In the liquid crystalline compound used in the present invention, liquid crystal molecules having a rod-like structure and a discotic structure are preferable.

  The liquid crystal compound used in the present invention may or may not have an epoxy group, an oxetanyl group, or a vinyloxy group. However, when the liquid crystalline compound does not have an epoxy group, oxetanyl group, or vinyloxy group, the composition for forming an optical functional layer is a non-liquid crystal having an epoxy group, oxetanyl group, or vinyloxy group in addition to the liquid crystalline compound. It is essential to include a functional compound.

(1) Polymerizable low-molecular liquid crystal The polymerizable low-molecular liquid crystal needs to contain one or more polymerizable groups in one molecule. Although it does not specifically limit as a polymeric low molecular liquid crystal, The liquid crystalline compound which has a (meth) acryloyl group, an epoxy group, an oxetanyl group, or a vinyloxy group, a mixture, etc. are mentioned. Such liquid crystalline compounds are disclosed in, for example, JP-A-4-227684, JP-A-9-111240, JP-A-10-182556, JP-A-11-513019, JP-A-2000-98133, What is shown by the liquid crystalline compound of Unexamined-Japanese-Patent No. 2002-69450, Unexamined-Japanese-Patent No. 2003-96066, and Unexamined-Japanese-Patent No. 2004-123597 can use it conveniently.

  Polymerizable low-molecular liquid crystals can be polymerized by ultraviolet irradiation or heating, but polymerization by ultraviolet irradiation is preferable in terms of reactivity.

  The use of a liquid crystal compound having a plurality of polymerizable functional groups in one molecule is preferable because an optical element having good heat resistance can be obtained. One type of liquid crystal compound can be used, but a mixture of two or more types may be used in order to expand a temperature range showing liquid crystal or to control birefringence.

  As an example of the polymerizable liquid crystal compound having a plurality of polymerizable functional groups (polymerizable groups) in one molecule, for example, the following general formulas (9), (10), (11), (12), ( And compounds represented by 13), (14), and (15).

  The general formula (14) is a liquid crystal compound having a (meth) acryloyl group and a vinyloxy group, and the general formula (15) is a liquid crystal compound having a (meth) acryloyl group and an oxetanyl group.

  In addition, examples of the polymerizable liquid crystal compound in which one polymerizable group is contained in one molecule include compounds represented by the following general formulas (16) and (17).

(2) Polymer liquid crystal When a polymer liquid crystal is used as the liquid crystalline compound contained in the composition for forming an optical functional layer used in the optical functional layer of the optical element of the present invention, the polymer liquid crystal includes It is desirable to have an epoxy group, an oxetanyl group, or a vinyloxy group. When the polymer liquid crystal does not have an epoxy group, oxetanyl group, or vinyloxy group, the composition for forming an optical functional layer is a non-liquid crystalline compound having an epoxy group, oxetanyl group, or vinyloxy group in addition to the liquid crystalline compound. It is essential to include. Examples of preferred polymer liquid crystals in the present invention include polymer liquid crystals having an oxetanyl group obtained by radical polymerization of the monomer represented by the general formula (15). Or the copolymer of the monomer of General formula (15) and General formula (16), the copolymer of the monomer of General formula (1) and General formula (16), General formula (2), and General formula (16) The copolymer of a monomer and the copolymer of the monomer of General formula (3) and General formula (16) may be sufficient.

Non-liquid crystalline compound having an epoxy group, an oxetanyl group, or a vinyloxy group:
The component (D) is a compound having an epoxy group, an oxetanyl group, or a vinyloxy group, and may be a liquid crystal compound or a non-liquid crystal compound. Among these, the following compounds etc. are mentioned to a polyfunctional epoxy compound and a polyfunctional oxetane compound as a non-liquid crystalline compound.

i) Polyfunctional epoxy compound As the polyfunctional epoxy compound, any compound, polymer, or prepolymer containing two or more oxirane ring structures in the molecule can be used. The epoxy resin used here includes bisphenol A type epoxy resin, bisphenol F type epoxy resin, resorcin type epoxy resin, tetrahydroxyphenylmethane type epoxy resin, tetrahydroxyphenylethane type epoxy resin, phenol novolac type epoxy resin, cresol novolac. Examples include type epoxy resins, alicyclic compound type epoxy resins, aliphatic epoxy resins, epoxidized polybutadiene, epoxidized styrene / butadiene rubber, monoallyl diglycidyl isocyanuric acid, and the like. Examples of the polyfunctional alicyclic epoxy compounds include Celoxide 2021 (trade name), Celoxide 2080 (trade name), Epolide GT300 (trade name), Epolide GT400 (trade name), EHPE3150 (trade name), etc., manufactured by Daicel Chemical Industries. Is done.

ii) Polyfunctional oxetane compound As said polyfunctional oxetane compound, the compound represented by following General formula (18) is mentioned.

[In Formula (18), R ₅ represents a hydrogen atom, a methyl group, an ethyl group, a propyl group or a butyl group, such as an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, An aryl group, a furyl group or a thienyl group. R ₆ is, for example, a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, or a linear or branched poly (alkyleneoxy) such as a poly (ethyleneoxy) group or a poly (propyleneoxy) group. ) Group, propenylene group, methylpropenylene group or other linear or branched unsaturated hydrocarbon group, carbonyl group, alkylene group containing carbonyl group, alkylene group containing carboxyl group, alkylene group containing carbamoyl group, etc. is there. R ₆ may also be a polyvalent group selected from the groups represented by the following general formulas (19) and (20).

(In the formula (19), R ₇ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, a methoxy group, an ethoxy group, a propoxy group or a butoxy group. A C 1-4 alkoxy group, a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkyl carboxyl group, a carboxyl group, or a carbamoyl group.

(In Formula (20), R ₈ is an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ or C (CH ₃ ) ₂ ]

Non-liquid crystalline compound having (meth) acryloyl group and epoxy group in the molecule:
A compound having a (meth) acryloyl group and an epoxy group in the molecule belongs to the component (C), and compounds of the following general formula (31) to general formula (34) are exemplified. As an example of a method for synthesizing a compound having a (meth) acryloyl group and an epoxy group, a compound having a (meth) acryloyl group and a carboxyl group (for example, a reaction product of pentaerythritol triacrylate and succinic anhydride, or (meth) acrylic) Acid) and a polyfunctional epoxy compound, and the following formulas (31) to (34) belong to this.

(In the formulas (21) to (30), R ₁ is a hydrogen atom or a methyl group, m is an integer of 1 to 6, and n is 0 or an integer of 1 to 6.)

(In the formulas (31) to (34), R ₉ is

Or

, R ₁ and R ₃ are hydrogen or a methyl group, p and q are 0 or an integer, and the sum of p and q is 2 to 8. )

Non-liquid crystalline compound having (meth) acryloyl group and oxetanyl group in the molecule:
A compound having a (meth) acryloyl group and an oxetanyl group in the molecule belongs to the component (C), and includes a compound represented by the following general formula (35).

(In the formula (35), R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 1 to 12 carbon hydrogen or branched optionally carbon, m is an integer from 1 to 6, n Is 0 or an integer from 1 to 6.)

  In the compound represented by the formula (35), (meth) acryloxymethyl-3-ethyloxetane is particularly preferable.

Compound having (meth) acryloyl group and vinyloxy group in the molecule:
A compound having a (meth) acryloyl group and a vinyloxy group in the molecule belongs to the component (C) and includes the following compounds.

  (Meth) acrylic acid 2-vinyloxyethyl, (meth) acrylic acid 3-vinyloxypropyl, (meth) acrylic acid 1-methyl, 2-vinyloxyethyl, (meth) acrylic acid 2-vinyloxypropyl, (meth) acrylic acid 4 -4-vinyloxycyclohexyl vinyloxybutyl (meth) acrylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, p-vinyloxymethylphenylmethyl (meth) acrylate, Examples include 2- (vinyloxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, and 2- (vinyloxyisopropoxy) propyl (meth) acrylate. Of these, 2- (vinyloxyethoxy) ethyl (meth) acrylate is preferable.

Photopolymerization initiator:
If necessary, a photopolymerization initiator can be added to the composition for forming an optical functional layer according to the present invention. The photopolymerization initiator is appropriately selected from a radical photopolymerization initiator, a photocationic polymerization initiator, and the like according to the type and amount of the polymerizable group of the liquid crystalline compound or the non-liquid crystalline compound.

  Examples of the radical photopolymerization initiator include benzyl, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-benzoyl-4′-methyldiphenyl sulfide, benzylmethyl ketal, dimethylaminomethylbenzoate, 2 -N-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3'-dimethyl-4-methoxybenzophenone, methylobenzoyl formate, 2-methyl-1- (4- (methylthio) phenyl ) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2-hydroxy- 2-me Rupropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1- On, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 1-chloro-4-proxythioxanthone Can do. In addition to the photopolymerization initiator, a sensitizer can be added within a range that does not impair the object of the present invention.

Photocationic polymerization initiators include sulfonic acid esters, imide sulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η ⁶ -benzene) (η ⁵ -cyclopenta Dienyl) iron (II) and the like are exemplified, and more specifically, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosiphthalimide and the like are exemplified, but not limited thereto. .

  Examples of photo radical polymerization initiators and photo cationic polymerization initiators include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, iron arene complexes, etc. More specifically, diphenyliodonium, ditolyliodonium, iodonium chloride such as bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium, bromide, borofluoride, hexafluorophosphate salt, Iodonium salts such as hexafluoroantimonate salt, chlorides of sulfonium such as triphenylsulfonium, 4-tert-butyltriphenylsulfonium, tris (4-methylphenyl) sulfonium, bromide, borofluoride, hex Sulfonium salts such as fluorophosphate salts and hexafluoroantimonate salts, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2-phenyl-4,6-bis (trichloromethyl) -1, 2,4,6-substituted-1,3,5 triazine compounds such as 3,5-triazine, 2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine, etc. It is not limited to these.

  The addition amount of such a photopolymerization initiator is generally 0.01 to 20% by mass, preferably 0.1 to 10% by mass with respect to the photopolymerizable component in the composition for forming an optical functional layer. %, More preferably in the range of 0.5 to 5% by mass.

solvent:
The solvent used in the composition for forming an optical functional layer is not particularly limited as long as the liquid crystalline compound is dissolved and the orientation of the photo-alignment film is not impaired. Specifically, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; hydrocarbons such as benzene and hexane; ethers such as tetrahydrofuran and 1,2-dimethoxyethane; alkyl halides such as chloroform and dichloromethane; methyl acetate , Esters such as ethyl acetate, propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate; glymes such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether; amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; Etc.

<Photo alignment film>
The photo-alignment film is an alignment film capable of expressing an alignment regulating force by light irradiation, and a known compound can be used. For example, compounds such as a photodimerization type, a photoisomerization type, a photolysis type, etc., which are described in a review of “Liquid Crystal, Volume 3 (1) 3 to 16 (1999)” written by Masaki Hasegawa, can be given. Among them, the photodimerization type and the photoisomerization type are preferably used, and the alignment regulating force is expressed by irradiating the photo-alignment film with linearly polarized ultraviolet rays or obliquely irradiating non-polarized ultraviolet rays.

  Useful photoisomerizable compounds include compounds having azobenzene derivatives. Examples of the photodimerization compound include compounds having cinnamic acid derivatives, coumarin, chalcone, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, styrylpyridinium, uracil, quinolinone, maleimide or cinnamylideneacetic acid derivatives. Polymers having groups capable of photodimerization are preferred. In particular, a (meth) acrylic polymer or a maleimide polymer having a cinnamic acid derivative, coumarin, or chalcone in the side chain is preferably used (for example, JP-A-9-118717, JP10-506420A, Special Table). 2003-505561).

  Examples of units containing a photodimerizable group in the polymer preferably used in the present invention are shown in formulas (36) to (38).

(In formulas (36) to (38), R ₁ is hydrogen or a methyl group, R _{10 to} R ₁₇ are each independently hydrogen or an alkoxy group, and R ₁₈ is a linear or branched chain having 1 to 10 carbon atoms. An alkylene group, R ₁₉ and R ₂₀ are each independently hydrogen or an alkyl group, m is an integer of 1 to 20, n is an integer of 0 or 1 to 6, and t is 0 or 1. .)

  The composition for forming a photoalignment film used to form the photoalignment film in the optical element of the present invention contains a compound having one or more functional groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group. It is essential. The composition for forming a photo-alignment film has a functional group that causes a photodimerization reaction such as cinnamate, coumarin, or chalcone, in addition to one or more functional groups selected from the above epoxy group, oxetanyl group, and vinyloxy group. In addition, a compound having a monomer unit containing acrylic and maleimide as a main chain is used, or in addition to one or more functional groups selected from the above epoxy group, oxetanyl group, and vinyloxy group, azobenzene and the like It is desirable to use a compound having a functional group that causes photoisomerization and having a monomer unit containing acrylic and maleimide as the main chain.

  The composition for forming a photo-alignment film that can be preferably used in the present invention includes, for example, any one or more of units represented by the above formulas (36) to (38), and the following general formula (6) , (7) or a polymer containing any one or more of units represented by (8). Alternatively, a polymer containing any one or more of units represented by formulas (36) to (38) and a compound having one or more functional groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group are mixed. This can be used as a composition for forming a photo-alignment film.

(R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an optionally branched alkyl group having 1 to 12 carbon atoms, m is an integer of 1 to 6, and n is 0 or 1 to 6. Is an integer.)

  The amount of epoxy group, oxetanyl group, and vinyloxy group contained in the composition for forming a photo-alignment film is preferably larger in terms of adhesion to the optical functional layer, but if too large, a group capable of photodimerization is formed. Since the introduction amount of the unit to be included is reduced, the alignment regulating force of the liquid crystal is lowered.

  If necessary, a cationic polymerization initiator and a solvent can be added to the composition for forming a photo-alignment film used in the present invention.

  With the cationic polymerization initiator, the epoxy group, oxetanyl group, and vinyloxy group in the photo-alignment film are polymerized, and the strength of the photo-alignment film can be improved. As the cationic polymerization initiator, either a thermal cationic polymerization initiator or a photocationic polymerization initiator can be used. Examples of the thermal cationic polymerization initiator include onium salts such as sulfonium salts, ammonium salts, and phosphonium salts, and silanol / aluminum complexes.

  The solvent used in the composition for forming a photoalignment film is not particularly limited as long as it is a solvent in which the photoisomerizable compound and the photodimerized compound are dissolved.

<Barrier layer>
The barrier layer blocks the entry of substances from the support to prevent the plasticizer and other substances contained in the support from entering the photo-alignment film and disturbing the alignment performance when the support is plastic. Is to do. The barrier layer is a layer obtained by curing a barrier layer-forming resin composition made of ultraviolet ray and / or electron beam curable resin by ultraviolet ray or electron beam irradiation in that it blocks the intrusion of substances from the support. preferable.

  A resin composition for forming a barrier layer comprising an ultraviolet ray or an electron beam curable resin has two polymerizable groups such as a polymerizable vinyl group, allyl group, acryloyl group, methacryloyl group, isopropenyl group, epoxy group, and oxetane group. What has the above and forms a crosslinked structure or network structure by irradiation to an ultraviolet-ray or an electron beam is preferable.

  Of these active groups, an acryloyl group, a methacryloyl group or an epoxy group is preferred from the viewpoint of polymerization rate and reactivity, and a polyfunctional monomer or oligomer is preferred. Examples include ultraviolet curable polyol acrylates, epoxy acrylates, urethane acrylates, polyester acrylates, and epoxy resins. These resins are usually used together with known photopolymerization initiators. The photopolymerization initiator or photosensitizer contained in the ultraviolet and / or electron beam curable resin composition excluding the solvent component that volatilizes after coating and drying is particularly preferably 0.5 to 5% by mass of the composition. preferable.

  Among these, ultraviolet curable polyol acrylate is particularly preferable in terms of adhesion to the photo-alignment film. Specific examples of the polyol acrylate include monofunctional acrylates and methacrylates such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and phenoxyethyl (meth) acrylate; polyethylene glycol di (meth) acrylate, Methylolethane (tri) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, hexanediol di (meth) acrylate, tri Methylolpropane tri (acryloyloxypropyl) ether, tri (acryloyloxyethyl) isocyanurate, di (acrylo) Ruokishiechiru) isocyanurate, may be mentioned polyfunctional alcohol after adding ethylene oxide or propylene oxide (meth) were acrylated such as glycerin and trimethylol ethane.

  The film thickness after curing of the layer obtained by curing the ultraviolet ray and / or electron beam curable resin by ultraviolet ray or electron beam irradiation is suitably 0.05 μm or more and 30 μm or less, and preferably 0.1 to 15 μm. If the dry film thickness is too thick, the optical element may curl when it is on the film.

  When the support is untreated triacetyl cellulose, it is an ultraviolet and / or electron beam curable resin containing at least pentaerythritol triacrylate, di (acryloyloxyethyl) isocyanurate, or 1,6-hexanediol diacrylate. It is preferable in terms of adhesion to the support.

<Method for manufacturing optical element>
Next, an example of a preferable method for producing the optical element of the present invention will be described. If necessary, a resin composition for forming a barrier layer is applied on a support, and a crosslinked structure or a network structure is formed by irradiation with ultraviolet rays or electron beams and cured. Next, the resin composition for forming a photo-alignment film is applied and dried, and a photo-alignment film in which an alignment regulating force is generated by irradiating ultraviolet rays, particularly polarized ultraviolet rays, is formed. Next, the optical functional layer-forming composition is applied, dried, heated to the liquid crystal phase formation temperature, then subjected to polymerization by ultraviolet irradiation or heating, and the optical alignment film is aligned with the alignment regulating force of the photo-alignment film. A functional layer is formed.

[Example 1]
(Preparation of barrier layer)
30 parts by mass of pentaerythritol triacrylate (PET-30: trade name, manufactured by Nippon Kayaku Co., Ltd.), 10 parts by mass of 4-hydroxybutyl acrylate glycidyl ether, photopolymerization initiator (Irgacure 184: trade name, Ciba Specialty Chemicals) 2 parts by mass, methyl ethyl ketone 29 parts by mass, toluene 58 parts by mass on a triacetyl cellulose film (FT-T80UZ: trade name, manufactured by Fuji Photo Film Co., Ltd.) and bar coated at 80 ° C. for 3 minutes After drying, a barrier layer having a film thickness of 1 μm was produced by irradiating ultraviolet rays of 70 mJ / cm ² under a nitrogen atmosphere using a UV irradiation device (manufactured by Fusion UV Systems Japan, Inc., light source: H bulb).

(Preparation of alignment film)
Polymer 1 represented by the following formula (39) (GPC polystyrene-reduced weight average molecular weight Mw 100,000) is dissolved in cyclopentanone to form a 2% solids solution, and this solution is formed on the barrier layer prepared in the above step. After coating with a wire bar, it was heated and dried for 2 minutes with warm air at 80 ° C. to obtain a film having a dry mass of 0.07 g / m ² . An alignment film was produced by irradiating the film with 10 mJ / cm ^{2 of} linearly polarized ultraviolet light.

(Formation of optical functional layer)
8 parts by mass of a polymerizable liquid crystalline compound 1 represented by the following formula (40):

4-hydroxybutyl acrylate glycidyl ether (4HBAGE: abbreviation) 2 parts by mass, polymerizable initiator (Irgacure 907 (Irg907: abbreviation): trade name, manufactured by Ciba Specialty Chemicals) 0.5 part by mass of methyl ethyl ketone / toluene = 1 The solution for optical functional layer preparation was obtained as a 20% solid content solution. This solution was coated on the photo-alignment film prepared in the above step with a wire bar, and ultraviolet rays of 120 mJ / cm ² under a nitrogen atmosphere using a UV irradiation apparatus (manufactured by Fusion UV Systems Japan Co., Ltd., light source: H bulb). Was applied to cure the coating film. Thereby, a nematic liquid crystal layer was formed on the alignment film, and finally the optical element according to Example 1 was manufactured.

(Evaluation of adhesion)
A cross cut test according to JIS-K-5400 was performed. Specifically, 11 cuts were made vertically and horizontally at intervals of 1 mm on the coated surface of the nematic liquid crystal layer to make 100 1 mm square grids. A cellophane tape was affixed on this, peeled off quickly at an angle of 90 degrees, and the number of grids remaining without peeling was expressed as m and evaluated according to the following criteria.

○: 71 ≦ m ≦ 100 Adhesion is high and excellent.
Δ: 31 ≦ m <70
X: 0 ≦ m <30 Exfoliation is remarkable.
The evaluation results of the adhesion of the optical element of Example 1 are shown in Table 1 below.

(Evaluation of haze value)
Since this optical element is used for a display, a low haze value is required. The haze value was measured with a turbidimeter NDH2000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.) and evaluated according to the following criteria. The haze value tends to increase when the orientation of the liquid crystal layer is poor.

○: Haze value less than 0.5% ×: Haze value 0.5% or more The evaluation results of the haze value of Example 1 are shown in Table 1 below.

[Example 2]
The same as in Example 1 except that the polymer of the alignment film in Example 1 was changed from polymer 1 to polymer 2 represented by the following formula (41) (weight average molecular weight Mw in terms of polystyrene by GPC: 50,000). The optical element of Example 2 was produced. The evaluation results of the adhesion and haze value are shown in Table 1 below.

Example 3
The same as in Example 1 except that the polymer of the alignment film in Example 1 is changed from Polymer 1 to Polymer 3 represented by the following formula (42) (weight average molecular weight Mw 320,000 in terms of polystyrene by GPC). The optical element of Example 3 was produced. The evaluation results of the adhesion and haze value are shown in Table 1 below.

Example 4
Except for changing the polymer of the alignment film in Example 1 from Polymer 1 to Polymer 4 represented by the following formula (43) (polystyrene equivalent weight average molecular weight Mw 120,000 by GPC), the same as in Example 1 above. The optical element of Example 4 was produced. The evaluation results of the adhesion and haze value are shown in Table 1 below.

Example 5
8 parts by mass of the polymerizable liquid crystalline compound 1 represented by the formula (40), 2 parts by mass of 3,4-epoxycyclohexylmethyl acrylate, 0.5 parts by mass of Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) An optical element of Example 5 was produced in the same manner as in Example 4 except that a 20% solid content solution dissolved in toluene = 1/3 mixed solvent was used as a solution for producing an optical functional layer. The results of evaluating the adhesion and haze are shown in Table 1 below.

Example 6
The polymer of the alignment film in Example 5 was changed from the polymer 4 to the polymer 5 represented by the following formula (44) (weight average molecular weight Mw in terms of polystyrene by GPC: 50,000). The optical element of Example 6 was produced. The evaluation results of the adhesion and haze value are shown in Table 1 below.

Example 7
8 parts by mass of the polymerizable liquid crystalline compound 1 represented by the formula (40), 2 parts by mass of 2- (vinyloxyethoxy) ethyl acrylate, 0.5 part by mass of Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) An optical element of Example 7 was prepared in the same manner as in Example 2 except that a 20% solid solution dissolved in methyl ethyl ketone / toluene = 1/3 mixed solvent was used as the optical functional layer preparation solution. The results of evaluating the adhesion and haze are shown in Table 1 below.

Example 8
5 parts by mass of the polymerizable liquid crystalline compound 1 represented by the formula (40), 5 parts by mass of 4-hydroxybutyl acrylate glycidyl ether, 0.5 part by mass of Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) = An optical element of Example 8 was produced in the same manner as in Example 2 except that a 20% solid content solution dissolved in a mixed solvent was used as a solution for producing an optical functional layer. The results of evaluating the adhesion and haze are shown in Table 1 below.

Example 9
1 9 parts by mass of the polymerizable liquid crystalline compound represented by the formula (40), 1 part by mass of 4-hydroxybutyl acrylate glycidyl ether, and 0.5 part by mass of Irgacure 907 (manufactured by Ciba Specialty Chemicals) were mixed with methyl ethyl ketone / toluene = 1 / 3 An optical element of Example 9 was prepared in the same manner as in Example 2 except that a 20% solid solution dissolved in a mixed solvent was used as the optical functional layer preparation solution. The results of evaluating the adhesion and haze are shown in Table 1 below.

Example 10
8 parts by mass of polymerizable liquid crystalline compound 2 represented by the following formula (45), EHPE-3150 (trade name, manufactured by Daicel Chemical Industries, many epoxy groups in the molecule (about 15)) 2 parts by mass, Rhodorsil Photoinitiator 2074 (Trade name, manufactured by Rhodia, initiator of both radical polymerization and cationic polymerization) A solution of 20% solid content in which 0.5 part by mass is dissolved in a mixed solvent of methyl ethyl ketone / toluene = 1/3 is used as a solution for preparing an optical functional layer. The optical element of Example 10 was made in the same manner as Example 2 except for the above. The results of evaluating the adhesion and haze are shown in Table 1 below.

Example 11
7 parts by mass of polymer 6 represented by the following formula (46), EHPE-3150 (trade name, manufactured by Daicel Chemical Industries, Ltd.) A solution having a solid content of 2% dissolved in cyclopentanone and a solution for preparing an alignment film An optical element of Example 11 was made in the same manner as Example 1 except that. The results of evaluating the adhesion and haze are shown in Table 1 below.

[Comparative Example 1]
An optical element of Comparative Example 1 was produced in the same manner as in Example 1 except that the polymer of the alignment film was changed from polymer 1 to polymer 6 represented by the formula (46). The results of evaluating the adhesion and haze are shown in Table 1 below.

[Comparative Example 2]
Solid content in which 10 parts by mass of polymerizable liquid crystalline compound 1 represented by the formula (40) and 0.5 parts by mass of Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) were dissolved in a mixed solvent of methyl ethyl ketone / toluene = 1/3. An optical element of Comparative Example 2 was prepared in the same manner as in Example 1 except that the 20% solution was used as the optical functional layer preparation solution. The adhesion and haze evaluation results are shown in Table 1 below.

Abbreviations in Table 1 are the following names.
4HBAGE: 4-hydroxybutyl acrylate glycidyl ether
AVEE: 2- (vinyloxyethoxy) ethyl acrylate
The properties of the trade names in Table 1 are as follows.
EHPE-3150 (manufactured by Daicel Chemical Industries, trade name): many epoxy groups in the molecule (about 15) Rhodorsil Photoinitiator 2074 (trade name, made by Rhodia): initiator for both radical polymerization and cationic polymerization

  The optical element of the present invention is excellent in durability because of excellent adhesion between the photo-alignment film and the optical functional layer. The optical element of the present invention is useful for, for example, a retardation plate, a polarizer, a color filter for display, and the like.

It is a figure which shows one example of the basic layer structure of the optical element of this invention. It is a figure which shows another example of the fundamental layer structure of the optical element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Optical alignment film 3 Optical function layer 4 Barrier layer

Claims (11)

An optical element comprising at least a support, a photo-alignment film capable of expressing an alignment regulating force by light irradiation, and an optical functional layer comprising a liquid crystalline compound,
The photo-alignment film is formed from a composition for forming a photo-alignment film containing a compound having one or more groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group,
The optical functional layer is formed from a composition for forming an optical functional layer containing a compound having at least one group selected from an epoxy group, an oxetanyl group, and a vinyloxy group. . 2. The optical element according to claim 1, wherein the composition for forming an optical functional layer includes a liquid crystalline compound having at least one group selected from component (A): an epoxy group, an oxetanyl group, and a vinyloxy group. The composition for forming an optical functional layer is at least a component (B): a liquid crystalline compound having a (meth) acryloyl group, and
Component (C): The optical element according to claim 1, comprising a compound having a (meth) acryloyl group in the molecule and one or more groups selected from an epoxy group, an oxetanyl group, and a vinyloxy group. . The optical element according to claim 3, wherein the compound of the component (C) is represented by the following general formula (1), (2), (3), (4), or (5).
(R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an optionally branched alkyl group having 1 to 12 carbon atoms, R ₃ is hydrogen or a methyl group, and m is an integer of 1 to 6. N is 0 or an integer of 1 to 6, p and q are 0 or an integer, and the sum of p and q is 2 to 8.) The composition for forming an optical functional layer is at least a component (B): a liquid crystalline compound having a (meth) acryloyl group, and
(D) Component: The optical element of Claim 1 containing the polyfunctional compound which contains 2 or more of functional groups chosen from the epoxy group, the oxetanyl group, and the vinyloxy group in a molecule | numerator. The optical functional layer-forming composition has at least component (E): a (meth) acryloyl group and a liquid crystalline compound having at least one group selected from an epoxy group, an oxetanyl group, and a vinyloxy group. As well as
(D) Component: The optical element of Claim 1 containing the polyfunctional compound which contains 2 or more of functional groups chosen from the epoxy group, the oxetanyl group, and the vinyloxy group in a molecule | numerator.   7. The optical functional layer forming composition includes a liquid crystal compound and a non-liquid crystal compound, and a mass ratio of the liquid crystal compound and the non-liquid crystal compound is 60/40 or more and less than 100/0. The optical element according to item 1.   The total of epoxy group, oxetanyl group and vinyloxy group contained in the composition for forming an optical functional layer is 0.3 mmol or more per 1 g of components other than the solvent in the composition for forming an optical functional layer. Claim   The optical element according to any one of claims 1 to 8, wherein the composition for forming a photoalignment film includes a compound having a group capable of photodimerization. The optical element according to claim 9, wherein the compound having a photodimerizable group is a polymer containing a unit represented by the following general formula (6), (7) or (8).
(R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an optionally branched alkyl group having 1 to 12 carbon atoms, m is an integer of 1 to 6, and n is 0 or 1 to 6. Is an integer.)   The optical element according to claim 1, further comprising a barrier layer between the support and the photo-alignment film.